In vitro toxicity of antibacterial metal oxide nanoparticles: effects on 2D and 3D skin and lung models

The massive use of nanomaterials (NMs) in many fields of application poses a growing concern about human safety, especially when skin contact and/or inhalation occur. In this work, the toxicity of different antibacterial metal oxide nanoparticles (MeO-NPs) used for the coating of biomedical textiles, was assessed using different 2D and 3D in vitro models of the skin and the lung. NPs suspensions were characterized by TEM and DLS, while NPscoated textiles were subjected to extraction procedure in artificial sweat (AS, pH 4.7 and 6.5). The release of NPs and/or ions from the textiles after extraction was evaluated through ICPOES. For skin contact exposure, Epiderm™ 3D in vitro models (MatTek) were used according to the Skin Corrosion OECD TG 431 protocol and to the Skin Irritation test (ISO/TC 194/WG 8 for Medical Devices). Balb/3T3 fibroblasts were used as 2D model of wounded skin. For inhalation exposure, A549 lung cell monocultures and an in vitro model of the lung barrier cultivated at the Air Liquid Interface (ALI) were used. Data evidenced that, even if MeONPs have great potential in the biomedical field, their ability to induce toxic responses may vary depending on the different properties of the NPs and the characteristics of the different models used. In conclusion, in order to fulfil the knowledge gaps and ensure a safe and sustainable design of NMs, it would be pivotal to include exposure and hazard assessment in the experimental researches.